And indeed, all patients were able to synch leg, ankle, and toe movements in unison with the rise and fall of a wave displayed on a computer screen. Three out of four were able to change the force at which they flexed their legs (depending on the intensity of three different auditory cues).


"The fact that the brain is able to take advantage of the few connections that may be remaining, and then process this complicated visual, auditory, and perceptual information, is pretty amazing," added study co-author Reggie Edgerton. "It tells us that the information from the brain is getting to the right place in the spinal cord, so that the person can control, with fairly impressive accuracy, the nature of the movement."

The new study shows that the work done on Summers was no fluke.

"The implications of this study for the entire field are quite profound and we can now envision a day where epidural stimulation might be part of a cocktail of therapies used to treat paralysis," noted co-author Susan Hawley.


Read the entire study at Brain: "Altering spinal cord excitability enables voluntary movements after chronic complete paralysis in humans."

Images: Susan Harkema/The Lancet/Elsevier; the University of Louisville.